19704 - General Physics B

Learning outcomes

At the end of the course the student has assimilated and is able to apply the knowledge on the basic concepts of the General Physics in the language of the Mathematical Analysis, of the Integral and Vector Calculus; he has assimilated and is able to apply the technical-scientific methodology needed in order to face in quantitative terms the physics problems.

Course contents

1. Electrostatics. The 4 fundamental forces of the nature: gravitational interaction, weak interaction, electromagnetic interaction, strong interactions. Matter particles: quark and leptons. Interaction particles: bosons. Triboelectricity, lightning and thunderbolts. The principle of superposition. Continuous distributions of electric charge. The electric field. Electric field representation by means of field lines. The flux of the electric field. The Gauss law for the electric field. Divergence of a vector field. The Gauss theorem (or divergence theorem). Local form of the Gauss law for the electric field. Electrostatic potential.
2. Conductor electrostatics. Dielectrics and conducting media. Charge distribution, electric field and potential inside conductors. Electrostatic induction. Electric field on conductor surface. Electric field in a cavity inside a conductor, electrostatic screen, Faraday cage. Complete induction. The meaning of grounding. Potential of a charged conducting sphere. The power of points. Conductor capacity. Capacitors and their capacity. Capacitors linked in series and in parallel.
3. The general problem of the electrostatics. Electrostatic energy of a point charge system. Electric dipole. Electrostatic energy of a charged capacitor. Electrostatic energy density associated with an electric field. Localization of the electrostatic energy. Locality of the energy conservation principle. Poisson and Laplace's equations. The general problem of the electrostatics.
4. Electric current. Electric current, Drude-Lorentz model, drift velocity and thermal velocity of the conduction electrons.current strength and current density. Ohm's law in the integral and local form, resistance, conductance, resistivity and conductivity. Resistors. Resistors linked in series and in parallel. Dissipated power, Joule's law. Superconductors. Electric generators. Non-electrostatic and non-conservative characteristic of the forces that move the electric charges in an electric generator. The Van der Graaf's generator. Direct-current circuits. Long-distance power lines: use of high voltages to reduce the power dissipation. Transient in a RC-circuit: charge and discharge of a capacitor.
5. Magnetic force. The interaction between two charged particles in uniform motion. Ampère-Biot-Savart law. Magnetic force and its characteristics. Continuous distribution of charge in motion. Local conservation of the electric charge, continuity equation in integral and local form. The magnetic field, Lorentz's force, magnetic force on a continuous distribution of charge in motion due to a magnetic field, magnetic field generated by a continuous distribution of charge in motion. Electric wires, first and second Laplace's formulae, Biot-Savart law, magnetic field generated by a circular loop and by a solenoid. Force between two rectilinear electrical wires. Definition of the Ampère unit.
6. The equations of the magnetic field. Tubes of flux. Flux of the magnetic field. Gauss law for the magnetic field in integral and local form. Absence of the magnetic charge. Circulation of the magnetic field. Ampère-Maxwell's law in integral and local form. Maxwell displacement current. Ampère-Maxwell's law and conservation of the electric charge. Calculations of magnetic fields using the Ampère-Maxwell's law: indefinite rectilinear electric wire, solenoid.
7. Electromagnetic induction. Null flux non-conservative electric fields. Circulation of the electric field. Faraday-Lenz's law in integral and local form. Induced electric field, electromotive force and induced current. The Maxwell's equations.
8. Electric circuits. Self inductance. Inductance of a solenoid. Energy accumulated in a solenoid covered by a stationary electric current. Energy density associated to a magnetic field. Mutual inductance. Transformers. Mean value and root-mean-square value (effective value). Alternate current. Galileo Ferrari's formula. Circuit elements: resistors, capacitors, inductors and electromotive force generators. Electric networks, Kirchhoff's laws and Maxwell's rule. Transient in a RL-circuit. Extracurrents. Oscillating RLC-series circuit: analogy with the mechanical damped oscillator. The complex formalism. Stationary state of a RLC-series circuits submitted to an alternate electromotive force. Impedance, resistance, reactance, admittance, conductance and susceptance.
9. Electromagnetic waves. Density of the energy flux, Poynting vector. Energy conservation and Poynting theorem. Electromagnetic waves, d'Alambert's equation. Solutions of the d'Alambert's equation: plain progressive and regressive waves, spherical converging and diverging waves. Transversality of the electromagnetic waves. Relation between the electric and the magnetic field in an electromagnetic wave. Linear, circular and elliptic polarization. Right-handed and left-handed polarization. Non-polarized and partially polarized electromagnetic waves. Method of polarization of the electromagnetic waves: selective emission, selective absorption, single scattering and reflection. Perfect polarizer. Malus's law. Brewster's angle. Birefringent plates. Application: anti-glare glasses, liquid crystals.
10. Thermodynamic systems and molecular motions. Extension of the principle of energy conservation to dissipative forces: internal energy. Kinetic molecular theories. Relations between macroscopic thermodynamic quantities and microscopic mechanical quantities. Microscopic mechanical reversibility and macroscopic thermodynamic irreversibility. Free expansion of a gas and spontaneous compression: Poincaré's time. Intensive and extensive quantities. Thermodynamical equilibrium. Adiabatic and diathermic walls. Thermal contact. Thermal equilibrium between two thermodynamical systems. Thermometers: thermometric materials, thermometric properties and thermometric functions. Zeroth law of thermodynamics. Thermometer calibration. Fixed points: normal melting point, normal boiling point and triple point. Ideal gas thermometer. Units of measurement of the temperature. International temperature scale. Thermodynamic transformations. Quasi-statics thermodynamic processes. Clapeyron diagram. Adiabatic quasi-statics thermodynamic processes of a gas. Quasi-statics isochoric heating and cooling of a gas. Equation of state of an ideal gas. Mole and Avogadro's number. Atomic mass and molecular mass: the unified atomic mass unit. Isothermal processes of real fluids. Critical temperature. Saturated vapor pressure. Changes of the aggregation state. Van der Waals equation: co-volume and internal pressure constant. Ebullition. Bubble chambers.
11. First principle of the thermodynamics. Average molecular kinetic energy. The work in a quasi-static transformations of a fluid. Adiabatic work. Internal energy. Amount of heat. The first principle of the thermodynamics. Heat capacity, specific heat and molar heat. Latent heats. Ideal gases. Technical work and enthalpy. Property of ideal gases. Quasi-static adiabatic transformations of an ideal gas: Poisson's formulae.
12. Second principle of the thermodynamics. Reversible and irreversible transformations. Heat engines. Efficiency of a heat engine. Carnot's cycle. Refrigerating systems. Second principle of the thermodynamics: Kelvin-Planck and Clausius statements and their equivalence. Impossibility of the perpetual motion of first and second species. The Carnot's theorem. Absolute thermodynamic temperature. The Clausius's theorem. Entropy. The law of the increase of the entropy. Example of calculations of entropy variation in a reversible or irreversible thermodynamic process. The equation of the internal energy. The equation of the enthalpy. The equations of the TdS. Helmholtz and Gibbs's thermodynamic potentials and their properties.

Readings/Bibliography

• Copy of the transparencies presented during the course, available on World Wide Web at the Alma Mater Digital Library: Collezione AMS Campus - AlmaDL - Trasparencies.
• Question and exercises for the assessment, available on World Wide Web at the at the Alma Mater Digital Library: Collezione AMS Campus - AlmaDL - Questions/Esercizes.
• Bertin, Poli, Vitale, Fondamenti di Termodinamica, Progetto Leonardo, Esculapio, Bologna.
• Bertin, Semprini Cesari, Vitale, Zoccoli, Lezioni di elettromagnetismo, Progetto Leonardo, Esculapio, Bologna.
• Focardi, Massa, Uguzzoni, Fisica Generale, Elettromagnetismo, Casa Editrice Ambrosiana, Milano.
• Focardi, Massa, Uguzzoni, Fisica Generale, Onde e Ottica, Casa Editrice Ambrosiana, Milano.
• Amaldi, Bizzarri, Pizzella, Fisica Generale, elettromagnetismo, relatività, ottica, Zanichelli, Bologna.
• Feynmann, Leighton, Sands, The Feynmann Lectures on Physics, vol II, Addison-Wesley.
• Rosati, Casali, Problemi di Fisica Generale, volume 2, elettricità, magnetismo, elettrodinamica e ottica, seconda edizione, Casa Editrice Ambrosiana, Milano.
• Salandin, Pavan, Problemi di Fisica risolti e commentati, volume 2, Casa Editrice Ambrosiana, Milano.

Teaching methods

• During the frontal lessons slides are shown by means of a projector connected to a MacBook.
• Such transparencies are made available to the students before the lecture by means of World Wide Web, in order to reduce the time and the work of mere transcription during the lessons.
• The proposed practices demand the use of the pocket calculator.
• To communicate with students, the mailing list domenico.galli.fisica-B-forli of University Directory Service is widely used.

Assessment methods

• The assessment of the achieved learning outcomes in the Integrated Course of General Physics (I.C.) consists in two distinct exams, which may be taken in different days (in the same Academic Year) or in the same day: the exam of the module of General Physics A and the exam of the module of General Physics B.
• The module-exam for both the modules (General Physics A and General Physics B) is written and consists, in turn, in 2 parts.
• The first part of a module-exam consists of questions concerning the topics introduced during the lectures, with the aim of verifying that the student has deeply understood the physics principles and is able to apply them in formulating the laws which regulate specific physical phenomena; the students are required to write concise open answers; the assessment is based on accuracy, completeness, clearness and conciseness (in decreasing weight order).
• The second part of a module-exam consists of exercises relating to the topics introduced during the lectures, aimed to verify that the student is able to deal with real problems by using the physics principles and laws, in order to get the numerical values of the requested physical quantities, expressed in the proposed units, thus revealing experience in dimensional analysis and ability to execute calculations with the required approximation; the assessment is based on the accuracy of the numerical results.
• The pass of the module-exam requires a good rating in both the parts (question and exercises).
• In case of module-exam pass, the grade is the mean value between the grades of the two parts (questions and exercises).
• Full marks with distinction (laude) is attributed to a module-exam grade if both exam parts (question and exercises) show an excellent skill of the student.
• The global exam of the Integrated Course of General Physics (I.C.) is passed if both the module-exams (General Physics A and General Physics B) are passed.
• In case of global exam pass, the grade is the mean value between the grades of the two module-exams (General Physics A and General Physics B).
• Full marks with distinction (laude) is attributed to the global exam grade if both module exams (General Physics A and General Physics B) has been passed with distinction.
• Further details about the exam tests and their evaluation are available at the web page: “Evaluation of exam tests”.

Teaching tools

Projector, MacBook.

Office hours

See the website of Laura Fabbri